Arrangement for generating a 3D video signal

ABSTRACT

The invention relates to an arrangement for generating a 3D video signal, which produces a 3D effect when it is displayed on a screen, from an input video signal that is made up of frames, each of which has an odd field and an even field, where in order to generate the 3D video signal alternately an even field n and an odd field n−1 (or vice versa) and subsequently alternately an even field n+1 and an odd field n (or vice versa) are displayed, where in order to generate the 3D video signal a scan converter ( 4, 5 ) is used which can display two signals in the split screen mode, one of which is delayed by means of a special function memory ( 4 ) in the scan converter, where the non-delayed signal and the delayed signal are written, horizontally compressed by a factor of two, into a conversion memory ( 6 ) and, for the purposes of displaying on a screen, when they are read are scaled up by a factor of two in the horizontal direction.

The invention relates to an arrangement for generating a 3D videosignal, which produces a 3D effect when it is displayed on a screen,from an input video signal that is made up of frames. Each frame has anodd field and an even field. In order to produce the 3D effect and togenerate the 3D video signal, alternately an even field n and an oddfield n−1 are displayed. Subsequently, the in each case next fields,that is to say an even field n+1 and an odd field n, are alternatelydisplayed. Of course, this displaying can also take place in the inversemanner, that is to say for example an even field n−1 and an odd field nmay alternate.

In the case of such an alternate displaying of two fields from twosuccessive frames, the 3D effect is relatively clear, since movingobjects that are located relatively close to the camera have a higherangular velocity than objects that are further away. As a result, movingobjects are optically emphasized and a 3D effect is produced.

U.S. Pat. No. 5,682,437 discloses an arrangement which uses fields fromtwo different frames to produce such a 3D effect.

The disadvantage of this and other known arrangements for producing a 3Deffect in conventional 2D video signals is that in order to produce the3D effect considerable additional hardware must be used, including atleast some field memories.

It is an object of the invention to specify an arrangement of the typementioned above which makes it possible, in respect of television setscomprising scan converters, to drastically reduce the complexity ofproducing the 3D video signal.

This object is achieved according to the invention by the features ofpatent claim 1:

An arrangement for generating a 3D video signal, which produces a 3Deffect when it is displayed on a screen, from an input video signal thatis made up of frames, each of which has an odd field and an even field,where in order to generate the 3D video signal alternately an odd fieldand an even field, which originate from two successive frames, andsubsequently the identical fields of the in each case next frames arerecorded in the 3D video signal, where in order to generate the 3D videosignal a scan converter is used which can display two signals in thesplit screen mode, one of which is delayed by means of a specialfunction memory in the scan converter, where the non-delayed signal andthe delayed signal are written, horizontally compressed by a factor oftwo, into a conversion memory and, for the purposes of displaying on ascreen, when they are read are scaled up by a factor of two in thehorizontal direction and shifted horizontally such that they aredisplayed in the correct convergence.

Scan converters are in many cases provided in television sets in orderto double or increase the field frequency. For example, a video signalhaving a field frequency of 50 Hz is converted into a video signalhaving a field frequency of 100 Hz. Such a 100 Hz scan converter forthis purpose has a number of field memories and computing units.

The idea of the arrangement according to the invention is to use such ascan converter, as provided in any case in a large number of televisionsets, additionally to generate the 3D video signal or to produce the 3Deffect in the video signal supplied by the scan converter on the outputside. In particular, the field memories provided in any case in scanconverters may be additionally used for the suitable intermediatestorage of the fields for producing the 3D effect.

Scan converters that are able to display two signals in the so-calledsplit screen mode have, by virtue of their architecture, all the meansnecessary to process two video signals independently of one another.They thus have two signal paths for processing two video signals. Thisproperty is used in the arrangement according to the invention toprocess the abovementioned field sequences separately from one anotherin the two paths.

Thus, the odd fields of the frames are processed in one path and theeven fields of the frames are processed in the other path, and these arethen displayed alternately on the output side in the manner describedabove. In a scan converter which can display two signals in the splitscreen mode, there is at least one memory provided for specialfunctions, such as for movement estimation, time base correction orsimilar functions for example. One of the two field sequences is readfield by field into this memory. This sequence of fields is thus delayedby a desired duration, usually by the duration of one frame. The otherpath of the scan converter processes in each case the other fieldsequence and reads the latter into a conversion memory. The fieldsequence read into the special function memory is read from said memoryand likewise written into the same conversion memory. Thus the two fieldsequences are then present in the conversion memory, with one fieldsequence being delayed by a desired value relative to the other fieldsequence.

In scan converters provided to display two signals in the split screenmode, the conversion memory is configured such that the two signals arewritten into the conversion memory in a form scaled down, that is to saycompressed, horizontally by a factor of 2. In the arrangement accordingto the invention, the two fields are read from the conversion memoryagain and scaled up in the horizontal direction by a factor of 2 so thatboth fields again exist in the normal size. The fields may then bedisplayed alternately in the manner described above, by being read inthe appropriate sequence from the conversion memory.

The arrangement according to the invention uses all the hardwarepossibilities of a scan converter that can display two signals in thesplit screen mode. No additional hardware elements are required togenerate the 3D video signal. The changes which need to be made to ascan converter in order to generate such a signal for implementing thearrangement according to the invention are limited to software changes.

According to two refinements of the invention as claimed in claims 2 and3, the arrangement according to the invention has on the input side twomultistandard digital decoders, of which one processes the odd fieldsand one processes the even fields.

Such multistandard decoders also have possibilities for scaling theimage sequences processed by them.

As claimed in claim 2, that one of the two multistandard decoders whichsupplies the fields directly to the conversion memory is also used toperform such a horizontal scaling by a factor of 2, so that the fieldssupplied by this multistandard decoder are assigned to the conversionmemory in a form already scaled down by a factor of 2. The othermultistandard decoder, which processes the other field sequence, doesnot perform any such scaling down. This is carried out only when thedata are read from the special function memory and then read into theconversion memory. This is readily possible at this point since scanconverters have enough computing capacity to perform this scaling down.

Another advantageous possibility is that as claimed in claim 3,according to which the two multistandard decoders are in each case usedto scale down by a factor of two the fields supplied by them. In thiscase, the fields are also written into the special function memoryalready in scaled-down form and then are transferred unchanged from thismemory into the conversion memory.

In both solutions as claimed in claims 2 or 3 there is no additionalhardware requirement since scan converters which are suitable forprocessing two video signals have two such multistandard digitaldecoders.

Besides generating the video signal with a 3D effect in the mannerdescribed above, the arrangement according to the invention mayadditionally be used to convert the input video signal having a fieldfrequency of 50 Hertz into a 3D video signal having a field frequency of100 Hertz. The abovementioned field sequences are doubled in theprocess; for example a field n, a field n−1, a field n and a field n−1are displayed in this sequence. The respectively next fields are thenlikewise displayed twice alternately.

The invention will be further described with reference to examples ofembodiments shown in the drawing to which, however, the invention is notrestricted.

The single FIGURE shows, in the form of a block diagram, an arrangementaccording to the invention for generating a 3D video signal from aconventional input video signal.

The input video signal designated V_(E) in the FIGURE may be aconventional video signal having a field frequency of 50 Hertz, forexample of the PAL standard.

In the arrangement according to the invention, this signal is convertedinto a 3D video signal which is designated V_(3D) in the FIGURE. Thearrangement according to the invention additionally doubles the fieldfrequency, so that the 3D video signal has a field frequency of 100Hertz. The embodiments are 100 Hz scan converters. Scan convertersproducing another field frequency, for example 75 Hz, may also be usedas desired.

The arrangement according to the invention on the input side has twodigital multistandard color decoders 2 which on the output side supplyin each case a field stream TB₁ and TB₂.

One of the digital multistandard color decoders in each case suppliesthe even fields and one the odd fields. In the text which follows, itwill be assumed that the first digital multistandard color decodersupplies in the field sequence TB₁ the in each case odd fields of theinput video signal V_(E) and the second digital multistandard colordecoder 2 supplies in its output field sequence TB₂ the in each caseeven fields of the input video signal V_(E).

The arrangement has a 100 Hz scan converter which consists of circuitblocks 3 and 5 that are provided to generate a 100 Hertz signal. This100 Hz scan converter may be provided for further purposes, such asmovement estimation and movement correction, zooming of images, jittercorrection or the like for example. 100 Hz scan converters which areprovided to display two image signals in the split screen mode, in whichtwo signals are displayed next to one another in horizontally offsetform, have two signal paths for the independent processing of twosignals. This property is used in the arrangement according to theinvention to process the two field streams TB₁ and TB₂.

Furthermore, the memories provided in any case in the 100 Hz scanconverter, which memories are designated 4 and 6 in the FIGURE, arelikewise used to produce the 3D effect.

In the first circuit block 3 of the 100 Hz scan converter there is amemory 4 which is usually provided for special functions produced bymeans of the 100 Hz scan converter. The second field stream TB₂, whichis supplied by the second digital multistandard color decoder 2, is readinto this special function memory 4.

In the circuit block 5 of the 100 Hz scan converter there is a memory 6which is used as conversion memory and into which 2 fields may be readsuch that they can be displayed in the above-described split screen modeduring normal operation of the 100 Hz scan converter. In the arrangementaccording to the invention, this conversion memory 6 is also used tostore two fields.

The first digital multistandard color decoder 1 supplies the fieldsequence TB₁ consisting of the odd fields of the frames, in a form thathas already been scaled down, that is to say compressed, horizontally bya factor of 2. The fields are written into the conversion memory 6 inthis scaled-down form.

The fields of the second field stream TB₂, which are initially storeduncompressed in the special function memory 4, are likewise scaled down,that is to say compressed, horizontally by a factor of 2 after they havebeen read from the memory 4 and before they are written into theconversion memory 6. Following this, in each case at least two fieldsare available in the conversion memory 6. Since the field stream 2 isdelayed by the duration of one frame relative to the field stream 1, ineach case an odd field of a frame n and an even field of a frame n−1 orn+1 are available in the conversion memory 6. In each case, there arethen two fields in the conversion memory, said two fields belonging tosuccessive frames, that is to say not to the same frame. On account ofthis selection of the fields, the above-described 3D effect is amplifiedsince in this way movements which have occurred in the time that haslapsed between the fields are emphasized in an amplified manner.

The fields are now in the conversion memory 6 but still in compressedform, as is normally provided for the split screen mode. However, sincethe fields are to be displayed sequentially in full on the screen, thefields are scaled up again by a factor of 2 in the horizontal directionwhen they are read from the conversion memory 6. This may be effected bymeans of a further circuit block 7, which may normally be provided forexample for display in the split screen mode. The images scaled up inthis way are generated in correct convergence with respect to oneanother, that is to say in the same position. The video signal thusprocessed in supplied on the output side as a 3D video signal V_(3D). Atthe same time a 100 Hz scan conversion can be performed so that the twofields stored in the conversion memory 6 alternately appear twice in the3D video signal V_(3D).

The arrangement according to the invention as shown in the FIGURE mayalso be configured such that not only the first digital multistandardcolor decoder 1 but also the second digital multistandard color decoder2 performs a scaling down of the field stream TB₂ supplied to it. Inthis case, the fields read into the special function memory 4 arelikewise read into this memory 4 in a form already scaled downhorizontally by a factor of 2. There is then no need for the scalingdown between the process of reading from the memory 4 and the process ofreading into the conversion memory 6.

The arrangement according to the invention thus uses a 100 Hz scanconverter to generate a 3D signal, where no hardware changes to the 100Hz scan converter are necessary. Rather, the changes are limited to anappropriate software adaptation.

1. An arrangement for generating a 3D video signal, which produces a 3D effect when it is displayed on a screen, from an input video signal that is made up of frames, each of which has an odd field and an even field, where in order to generate the 3D video signal a sequence of an odd field and an even field, each of which originate from a different one of two successive frames, and subsequently a sequence of a subsequent odd field and a subsequent even field, each of which originate from a different one of a next successive frame and a frame preceding the next successive frame, are provided in the 3D video signal, where in order to generate the 3D video signal a scan converter is used which can display two signals in a split screen mode, one of which is delayed by means of a special function memory in the scan converter, where the non-delayed signal and the delayed signal are written, horizontally compressed by a factor of two, into a conversion memory and, for the purposes of displaying on a screen, when they are read are scaled up by a factor of two in the horizontal direction and shifted horizontally such that they are displayed in the correct convergence.
 2. An arrangement as claimed in claim 1, characterized in that the arrangement has on the input side two digital multistandard color decoders, of which one supplies the odd (or even) fields to the special function memory and one supplies the even (or odd) fields to the conversion memory in a form that has already horizontally been scaled down by a factor of two, in that the fields are read from the special function memory, scaled down by a factor of two in the horizontal direction and written into the conversion memory.
 3. An arrangement as claimed in claim 1, characterized in that the arrangement has on the input side two digital multistandard color decoders, of which one supplies the odd (or even) fields to the special function memory in a form that has already horizontally been scaled down by a factor of two and one supplies the even (or odd) fields to the conversion memory in a form that has already horizontally been scaled down by a factor of two, in that the fields are read from the special function memory and written into the conversion memory.
 4. An arrangement as claimed in claim 1, characterized in that the input video signal has a field frequency of 50 Hertz and in that the arrangement supplies on the output side the 3D video signal having a field frequency of 100 Hertz, where the displaying takes place according to the scheme field n, field n−1, field n, field n−1, field n+1, field n, field n+1, field n and so on. 